Multiple values need to be separated by either semicolon followed by a space (e.g. '5.2; 3.3; <11.1'),
they may be in multiple lines or it can be a combination of it. To use multiple lines one can either
edit the value directly in DataWarrior or create a textfile with new-line encodings as '<NL>' (without the quotes).

DataWarrior allows a couple of modifiers to precede (<, >, <=, >=) or replace a numerical value (?, NaN).
Columns with numerical values and modifiers are still perceived as numerical data.